topic Re: Linux LVM exclusive mode ServiceGuard in Operating System - Linux

Linux LVM exclusive mode ServiceGuard

Christopher Caldwell — Mon, 21 Jul 2003 19:16:26 GMT

What are folks doing on Linux w/ServiceGuard since LVM on Linux apparently _doesn't_ support vg activation in exclusive mode (a somewhat dangerous problem).

Re: Linux LVM exclusive mode ServiceGuard

melvyn burnard — Tue, 22 Jul 2003 06:06:29 GMT

Go take a look at hte manuals at
http://www.docs.hp.com/hpux/ha/index.html#ServiceGuard%20for%20Linux
These explain how to do it.

Re: Linux LVM exclusive mode ServiceGuard

Karthik S S — Tue, 22 Jul 2003 08:33:22 GMT

It uses RAID tools to get similar exculsive environement.

Regards,
Karthik S S

Re: Linux LVM exclusive mode ServiceGuard

Krishna Prasad — Tue, 22 Jul 2003 11:26:18 GMT

We have only did testing with Red Hat Advanced Server and used the cluster software that came with that. I don't think it is Service Guard for Linux but it does work.

Re: Linux LVM exclusive mode ServiceGuard

Christopher Caldwell — Tue, 22 Jul 2003 22:05:26 GMT

So the md facility serves to ensure that the VGs aren't accessible by more than one host at a time?

Re: Linux LVM exclusive mode ServiceGuard

Karthik S S — Wed, 23 Jul 2003 03:48:47 GMT

Yeah you are right ...

raidstop / raidstart are the equivalent commands for vgchange ...

-Karthik S S

Re: Linux LVM exclusive mode ServiceGuard

Michael Morris — Tue, 29 Jul 2003 15:15:03 GMT

Using the MD driver to lock the disk appears to not work via multipath or raid1 md-modules. I'm curious as to how one uses MD to accomplish this. On one host at a time, my course of actions are:
(two Proliant DL380s fibre-connected to XP128 using Emulex cards)
1) ensure no MD modules are loaded
2) mdadm -A -R /dev/md0 /dev/sdb1 /dev/sdc1 (loads modules and activates md0)
3) vgchange -a y /dev/vgname
4) mount /dev/vgname/lvname /mnt/vgtest
5) while /dev/vgname/lvname is mounted on host-a, run steps 1-4 on host-b

I'm able to successfully do steps 1-4 on each server, and have /dev/vgname/lvname mounted on both servers at the same time. This is not a good thing. Are there any best practices to locking a disk in linux other than telling a person not to do it?